v1.5.1 is a bug fix release which addresses all known bugs in the
v1.5 serie.

* Fix block OS device detection on Linux kernel 3.3 and later.
Thanks to Guy Streeter for reporting the problem and testing the fix.
* Fix the cpuid code in the x86 backend (for FreeBSD). Thanks to
Sebastian Kuzminsky for reporting problems and testing patches.
* Fix 64bit detection on FreeBSD.
* Fix some corner cases in the management of the thissystem flag with
respect to topology flags and environment variables.
* Fix some corner cases in command-line parsing checks in hwloc-distrib
and hwloc-distances.
* Make sure we do not miss some block OS devices on old Linux kernels
when a single PCI device has multiple IDE hosts/devices behind it.
* Do not disable I/O devices or instruction caches in hwloc-assembler output.